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fix(macos): guard SSE task against superseded session on MainActor race #25426

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Merged
siddseethepalli merged 1 commit into from
Apr 14, 2026
Merged

fix(macos): guard SSE task against superseded session on MainActor race #25426

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9 changes: 9 additions & 0 deletions clients/shared/Network/EventStreamClient.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -277,6 +277,15 @@ public final class EventStreamClient {
sseTask = Task { @MainActor [weak self] in
guard let self else { return }

// A back-to-back call to `startSSEStream()` on the MainActor can
// cancel this task and invalidate `session` before it runs its
// first instruction. Calling `session.bytes(for:)` on an already
// invalidated session throws an ObjC NSGenericException from
// `-[__NSURLSessionLocal taskForClassInfo:]`, which is
// uncatchable in Swift and crashes the process with SIGABRT.
// Bail out before touching the session if we've been superseded.
guard !Task.isCancelled, self.sseSession === session else { return }

do {
let (bytes, response) = try await GatewayHTTPClient.stream(
path: "assistants/{assistantId}/events",
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